1. Field of the Invention
The invention is directed to a covering material capable of sorption for stacks and beds for mushroom cultivation.
2. Discussion of the Prior Art
Covering materials for stacks and beds for mushroom cultivation differ in substantial respects from the actual substrates for mushrooms. While the substrate consists for the most part of pre-treated horse manure, the covering material, as the name suggests, should cover the substrate, provide sufficient moisture for the mushrooms and create an environment in which an intensive formation of the fruiting body takes place. After the mushroom culture is harvested, the substrate is depleted with respect to nutrients. At the present time, black peat and, to a lesser extent, also white peat are mainly used for providing covering materials. For reasons of conservation of nature and to preserve peat bed locations, it is important to substantially eliminate the use of peat in mushroom cultivation.
Covering materials made from fibrous materials are generally known for use in agriculture. For example, U.S. Pat. No. 5,251,398 relates to a method for protecting plants from frost using hydrated cellulosic fibers.
EP-0 556 150 teaches a material in sheet form which is produced on a paper machine and can contain, among others, peat as fibrous material for use in agriculture for preventing erosion due to wind or water.
DE-44 16 030 A1 discloses a generic covering material which can be obtained through comminution of waste paper with the addition of water. A disadvantage in this process is that refuse which may possibly be contained in the waste paper, especially glass fragments, can lead to problems in the processing plant and this refuse causes additional disposal costs. Another disadvantage consists in that the waste paper market is subject to sharp fluctuations, so that there is no consistent supply of inexpensive raw material for the described process.